Sheet feeding mechanisms



Feb. 26,1957 H, J PICMG y v2,783,042

'Y SHEET FEEDING MEcHANIsMs 4 Sheets-Sheet 2 Filed Oct. 16, 1953 Feb. 26,1957 Hmmm@ v.2333.,042

SHEET FEEl-DING MECHANISMS v 4 sheets-snelst 4 Filed oct. v16,1955

'TL/26 A III Ill United States Patent Gestetner Limited, London, England, a Bn'tish company v Application October 16, 1953, Serial No. 386,609

Claims priority, application Great Britain January 21, 1953 V3 Claims. (Cl. 21717-42) This invention concerns sheet-feeding mechanisms and relates to mechanisms for feeding sheets in succession from a stack of paper resting on a platform, the mechanism being of the type comprising at least'one sheetfeeding roller (capable of vertical movement under its weight to engage the topmost sheet of the stack) which is supported from a reciprocating arm by a one-way clutch so that when the arm is advanced the roller is held against rotation and frictionally engages the topmost sheet of paper to advance it over the stack and when the arm is retracted the roller runs freely over the stack of paper.

When the stack of paper is nearly exhausted there is a tendency for the sheet-feeding roller to advance the entire stack instead of the topmost sheet only due to the friction between the platform and the lowermost sheet of the stack of paper being less than that between the paper sheets of the stack so that when the height of the stack l is reduced to a certain value the stack moves as a whole over the platform rather than the topmost sheet over the stack.

The object of the present invention is to kovercome or minimise this disability.

Another object is to provide a novel construction of platform which ensures that when the stack of paper has become reduced to a certain extent the frictional engagement between the stack and the platform is increased.

Yet a further object is to ensure that as the stack is used up after it has been reduced to said extent, the frictional engagement of the stack on the platform becomes greater. n v

A further object is the provision of means whereby the extent of the frictional engagement may be varied or predetermined.

Finally, it is an object of theinvention to ensure that in carrying out this invention the safe operation of the feed mechanism is not impaired.

A practical application of the present invention will now be described, by way of example, with reference to the accompanying drawings, whereof:

Figure 1 is a diagrammatic side view of a duplicating machine incorporating a sheet-feeding mechanism in accordance with the present invention,

Figure 2 is a perspective view showing the details of construction of the feed mechanism of the machine of Figure 1 to a larger size,

Figure 3 is a perspective view showing the sheetfeeding rollers and the stack-supporting platform,

Figure 4 is a plan view of a portion of the platform,

Figure 5 is a section on the line V-V of Figure 4, and,

Figure 6 is a side view of a part of the sheet-feeding mechanism showing certain details of construction thereof and partly in section.

As shown in Figure l, the duplicating machine comprises a frame 10 supported on a base 11, a platform 12 to support a stack 13 of paper which is to be fed through the machine for duplicating, a platform 14 on to which the duplicated copies are delivered to form a stack 15.

2,783,042 Patented Feb. 26, 1957 2 The machine is driven by a handle 16 which rotates a lower cylinder 17 through gearing (generally indicated at 18) a stencil 19 being secured around the lower cylinder 17 and an upper cylinder 20 in well known manner.

The edges of the stack of paper 13 are engaged by edge supports generally indicated at 21 (Figure 2), the edge supports being secured to the platform 12 and being preferably constructed as described in British Patent No. 727,182.

Referring now to Figure 2, the sheet-feeding mechanism, which is generally indicated by the reference numeral 25, comprises a pair of rollers 26 supported on a frame 27 (as later described in detail) which in turn is pivoted on a pin 28 carried by an arm 29 carried by a slide 30 which moves between guides 31 carried by the frame 10. The pinion 18 which is driven by the handle 16 is connected to an arm 32 by a connecting rod 33 and the arm has a pin 34 which enters a vertical slot 35 in the slide 3G, the arrangement being that with rotation of the handle 16 the arm 32 is oscillated to reciprocate the slide 30, arm 29 and the rollers 26 across the top of stack 13. The arm 32 is supported, at 35, from a face cam 36 which is rotated by a manual lever 37, the arrangement being that in one position of the lever 37 the face cam 36 enables the pin 34 to enter the slot 35 and in another position of the lever 37 the pin 34 is withdrawn from the slot 35 so that the drive from the handle 16 to the slide 30 is stopped.

The detailed construction of the rollers 26 and of the frame 27 will now be described with reference to Figures 3 and 6. The rollers 26 are faced with rubber and their peripheries are serrated or grooved (Figure 3). Both rollers are supported on a spindle 40 which extends across the frame 27, which is of channel section. Between the sidewalls 41 of frame 27 and mounted on thespindle 40 are a pair of V-grooved discs 42 secured on the spindle 40 for rotation with the rollers 26 and co-operating with each of the discs is a 'locking arm 43 pivoted, at 39, on frame 27. Each arm 43 has a curved end 44 which is urged by a spring 45 into engagement with the groove of the disc 42. The arrangement is that when the rollers 26 are rotated in the direction of the arrow a of Figure 6 the locking arms 43 are displaced against their springs 45 so that the rollers may freely rotate. This occurs when the slide 30 is reciprocated to draw the rollers 26 away from the cylinder assembly 17, 20. When the slide 30 is reciprocated to advance the rollers 26 to the cylinder assembly, rotation of the rollers 26 is prevented by the arm 43 which engages the discs 42 with increasing force as the rollers are urged to rotate.

The frame 27 is freely supported on the pin 28 and the weight of the frame and of the rollers 26 is such as to maintain the rollers in engagement with the topmost sheet of the stack 13. When the roller assembly is advanced the rollers 26 and frame 27 constitute a rigid link the angularity of which in relation to the surface of the paper stack ensures that, as arm 29 is moved forward, the rollers are pressed on to the topmost sheet of the stack which is consequently slid over the stack towards the cylinder assembly.

The platform 12, which is preferably made by casting, comprises a top 46 (Figures 4 and 5) reinforced on its rear surface by ribs or Webs 47. The upper surface of the top 46 is formed with a pair of grooves 48 which are separated by a rib 49. The top 46 at the ends of the rib 49 is slotted out as at 50 and each such slot portion has a threaded hole 51. The length of the grooves 48 is slightly greater than the travel of the rollers 26 and, as shown in Figure 3, the grooves are so disposed as to line, one each, beneath the track of the rollers 26. A plate 55 extends across the platform 12 and its ends are received in the slots 50 and secured in position by graso/1e 3 l a screw 56 entering holes 51. The upper surface of the plate 55 carries a strip A57 of sand paper or other material having a high coefhcient of friction, the strip 57 being arranged to lie between the inner cheeks of the rollers 26 as shown in Figure 3.

Slots extending through the top 46 of the platform may be provided in place of grooves 48.

While the stack comprises a considerable thickness of paper, the rollers 26 and the frame 27 operate to feed the sheets forward, as indicated but, having regard to the thickness of the stack, will not displace the stack downwardly into the grooves 48. When, however, the thickness of the stack is only that of about a dozen sheets of paper displacement of paper by the roller assembly will occur and as a consequence the frictional grip between the lowermost sheet of the stack and the platform 12 will be increased in two respects. Firstly, because the stack is deflected into the grooves 48 and, secondly, as a consequence of such deflection the portion of the stack between the grooves is pressed against the strip 57. By suitably selecting the material of the strip 57 the total frictional effect may be controlled.

The roller assemblyy 26 may be folded against the side of the frame 10, which folded position is indicated in Figure 6 by chain dotted lines. To this end, the arm 29 carries a pin 60 which extends across a pair of brackets 61, 62 secured to the slide 30. The pin 60 projects from the bracket 62, as at 63, to form a finger piece. The arm 29 has a pair of studs 64 which enter holes in the bracket 62, a spring 65 normally holding the arm 29 against bracket 62 with the studs 64 projecting through said bracket, the arm 29 being then in the horizontal position as shown in Figure 2. When it is desired to raise the rollers 26, the finger piece 63 is pressed to carry the arm 29 away from the bracket 62 against the compression of the springs 65 and when studs 64 disengage the bracket the arm 29 may be swung from the horizontal to the vertical position (Figure 6). When in the vertical position one of the studs 64 engages the upper surface of the bracket 62 and locks the arm 29 in its vertical position. A peg 70 projects radially from the pin 28 to enter a slot 71 in the frame 27, the frame being movable to a small extent lengthwise of the pin 28 so that when the frame 27 is turned to raise the rollers 26 away from the platform 12, the pin 70 may engage in the off-set part 74 of slot 71 to hold the framein the raised position. When the frame 27 is freely supported on the pin 28, it permits the rollers 28 to move vertically so that as the stack of paper decreases the rollers are automatically lowered. It is desired to limit the downward movement of the rollers 26 so that although they enter the grooves 48 they do not engage the bottom thereof, the lowermost position of the rollers 26 in relation to the groove being shown in Figure 5. To limit the downward movement, the arm 29 carries a peg 72 which is engaged by a peg 73 on the frame 27 when the latter reaches its lowermost position. Since the rollers are thus held from engaging the platform it is ensured that the feed mechanism is not seriously strained as would occur if the rollers, While heldiagainst rotation by the one-way clutch, during advance of the rollers, engaged the platform. For the same reason, if slots extending through the platform are provided instead of the grooves 48 the same mechanism (or a similar mechanism) will be provided to ensure that the rollers do not pass through the platform and engaging apart of the machine beneath the platform overstrain the feed mechanism.

I claim:

l. A sheet-feeding mechanism comprising a stack-supporting platform having a pair of parallel grooves in its upper surface extending in the direction in which the sheets are fed, a depending sheet-feeding arm pivotally supported above the platform for free downward movement, a sheet-feeding roller carried by said ann to enter each groove, a mechanism to reciprocate said arm so that the rollers travel lengthwise of the grooves and a one-way clutch which prevents rotation of the rollers when the arm is advanced in the direction in which thc sheets are fed, the arm being inclined downwardly and forwardly in the direction of the sheet feed at such an angle that when the arm is advanced it is thrust downwardly whereby the stack, when reduced to a certain extent, is forced in said grooves by said rollers, whereby when the stack of paper has become reduced to a certain extent the frictional resistance between the stack and the platform is increased.

2. A sheetfeeding mechanism as claimed in claim 1 in which the surface of the platform between the grooves offers a greater frictional resistance to the bottom sheet of the stack than is offered by the remainder of the said surface.

3. A sheet-feeding mechanism according to claim 2 wherein the surface of the platform between the grooves is'faced with a strip of material having a greater frictional resistance than the platform surface.

References Cited in the file of this patent UNITED STATES PATENTS 175,826 De Dreux Apr. 11, 1876 615,889 Parker Dec. 13, 1898 998,663 Wood July 25, 1911 1,127,991 Harbaugh Feb. 9, 1915 1,837,190 Post Dec. 22, 1931 1,964,498 Brasseur June 26, 1934 2,062,643 Edmunds Dec. 1, 1936 2,543,836 Dunn Mar. 6, 1951 

